Electric motor control



April 5, 1949. L. E. THOMPSON ELECTRIC MOTOR CONTROL Filed March 51, 1947 JNVENTOR LA WHENCEE 7710Mza5on; K

A TTOFAZEK Patented Apr. 5, 1949 UNITED STATES PATENT OFFICE ELECTRIC MOTOR CONTROL Lawrence E. Thompson, Marion, Ind.

Application March 31, 1947, Serial No. 738,394

3 Claims.

The object of the present invention is to provide for a combination reversible electric motor and switch, said switch being adaptable to select either of two motor energizing voltages and to reverse the direction of rotation of said motor.

The primary object of the present invention is to provide for a manually manipulable rotary switch having two independently operable switching sections, one of which is adapted to select either of two motor energizing potentials and the other adapted to change the direction of rotation of said motor by reversing the polarityof the voltage impressed on the starting winding of said motor.

A further object is to provide a rotary electric switch capable of being operated to vary the circuit constants of a single branch of a two circuit system without disturbing the constants of the other branch and vice versa.

The common expedient, well known to the art, to accomplish the above mentioned objects is a control box which is used in association with a reversible electric motor. This control box comprises, essentially, a number of bus bars so interchangeably arranged that the proper manual adjustment of them will efiect the desired circuit changes. The said bars are usually held in place by means of set screws and are provided with end slots to facilitate their being clamped in the proper positions. Obviously, this switching means is clumsy and cumbersome necessitating much time and effort to effect the desired changes, and furthermore, the commonly available sources of electric power are of sufficient magnitude to cause serious injury or death to any person coming into contact therewith; and since the bus bars are exposed and must be handled by the operator, a very desirable feature of danger presents itself, unless the motor is preliminarily disconnected from the power supply which is unnecessary with my switch.

My invention obviates the manual handling of the bus bars to effect desired circuit changes thereby overcoming the above-mentioned undesirable and dangerous features of the old switching system. By merely turning a knob, a 110 or 220 volt source of voltage may be applied to the electric motor as desired, and by merely turning another knob on the same switch the direction of rotation of said motor may be changed.

To the accomplishment of the above and related objects, my invention may be embodied in the form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that 2 change may be made in the specific constructions illustrated and described, so long as the scope of the appended claims is not violated.

Fig. 1 of the drawings is a side elevation of the illustrated embodiment of my invention;

Fig. 2 is a longitudinal cross-sectional View thereof;

Fig. 3 is a sectional view taken on the line 3-3 of Fig. 1 looking in the direction of the arrows;

Fig. 4 is a sectional view taken on line 4-4 of Fig. 1 looking in the direction of the arrows;

Fig. 5 is a sectional view taken on line 5-5 of Fig. 1, with the pressure washer removed, in association with a reversible electric motor which is illustrated by a schematic diagram;

Fig. 6 is a section taken on line 4-4 with the parts in a difierent position of adjustment; and

Fig. 1 is a section similar to that of Fig. 5, with the parts in a different position of adjustment.

Referring more particularly to the drawings, it will be seen in Figs. 1 and 2 that axially secured to concentric shafts l0 and II are two rotatable discs or wafers l2 and i3; disc l2 being suitably secured to shaft 10 and disc 13 being suitably secured to shaft ll. Knobs l4 and I5 are preferably formed integral with the opposite ends of these shafts, respectively, with knob 15 preferably the larger of the two.

The preferred method of securing the discs to their respective shafts is more clearly illustrated in Fig. 2. Shaft l l is preferably formed with its disc end square in shape and is loosely fitted into a correspondingly shaped hole in disc [3 to align said disc against sidewise movement. The lower end portion of shaft H] which extends beyond the corresponding end of shaft H is preferably formed in two sections, the upper of which being suitably formed to be loosely received in a suitably formed axial perforation in disc 12 and the lower of which being suitably formed to be journalled in the companion perforation in base plate I! which is constructed of some insulating material. A look ring member 18 is received on the projection of said last named journalled end to limit the upward axial movement of shaft 10. It is desirable that the whole assembly be firmly sandwiched and held together; and this may ordinarily be accomplished effectively through the medium of the spring contact members later to' be described. However, in certain installations, it may be desirable to add a coiled spring 15 sleeved on the shaft assembly and confined between the knob l5 and a fiber washer l6 bearing faces of said pins protrude beyond the faces of,

said discs an amount suificient to maintain a positive contact with their associated; contactor members to be described later. Both discs are further provided with rotational stopping means,

preferably by the shoulders I2'- and I3 formed by a quarter section of said discs having, respectively, smaller radii than the remaining portion of the discs. Stop, member I M in contiguousrelation, with the periphery of said' sections, is preferably formed. integral with contactor member 36.

Base plate I? is provided with four similar contact pins 23, 24:, 25, and 26 disposed 90 degrees apart on a circle coaxial and. congruent with the above mentioned circles. are electrically connected together by a bridge 2.! suitably fastened to the under side of said base plate. which connects contact pins 25 and 25, said bridge being provided. with an. upwardly bent ear 23 received in a recess 30; cut in the base plate I-'I"-. A contact rivet 31' is suitably-secured to the ear 29 and is arranged to engage contact rivet 32 secured to spring contact arm 33 fixed to base plate IT by any suitable fastening, means and preferably by a rivet 34-.

Contactor spring members 35: and 36, disposed diametrically opposite each other, best illustrated inv Figs. 5 and 7, are suitably formed and secured to base plate H byany suitablefastening means suchas rivets I35 and I36 and are there provided with solder lugs, such as those indicated by the reference numerals 37' and; 38. While these solderlugs are shown in the preferred embodiment of my invention, it is to be pointed out that they may be omitted and that lead wires may be soldered directly to said fastening means. The contactor 35' is formed to. conform substantially to a 90 degree are of a circle having a radius equal to that of the aforementioned circles and is disposed over disc I3 to engage contact pin 22 when disc I3 is rotated toits maximum counterclockwise position. Contactor- 35 integral with member 35 is of similar construction except that its arc length is substantially 45 disposed over disc I3 to engagepin 2Ii when disc I3 is rotated to. the same rotational position.

When disc I3 is rotated to its maximum clock-. wise position, contact pin 22 does not engage either of saidcontactors while contact pin 2I does,

engage contactor 36,.

The contactors 39' and 40' integral with memhere 39 and 40, respectively, arranged diametrically opposite each other and spaced 90 degrees relative to members 35 and 36, Figs. 4 and 6, are sandwiched: between discs I2- and I3, said members bein secured to said base plate I! by any suitable fastening means such as rivets I39 and I 40. The construction of saidcontactors is similar to that of contactor 36", said contactors being in continuous engagement with contact pins.

IE9- and 20, respectively, andwith contact pins 2I- 311x122, respectively.

Contact pins 23: and 24;-

Similarly fastened is a bridge 28 degrees and is,

When disc I2 is rotated to its maximum clockwise position, pins I9 and will register with pins and 24 respectively, and when said disc is rotated to its maximum counterclockwise position, pins I9 and 26 will register, respectively, with pins 23 and 26.

It will be clear that contact spring members 35, 36, 39 and 40 may be so biased as to exert a resilient downward pressure on the discs I2 and I3, thus holding the parts in the desired closely sandwiched relation; and that, in installations in, which the spring I6 and washer I6 are used, that spring will supplement the pressure effect of said: c ntactm m s A schematic diagram of a reversible electric Fig. 5.

The four field coils of the motor indicated by reference numerals 4|, 42, 43, and 44 are connected to the contactor members 35, 36, 39 and 40, respectively, by wires 45, 46, 41 and 48. A motor starter windin comprising the four coils 49, 50, 5I and 52 is wired to bridge 27 by wire 53: and to contact arm 33 by wire 54.

In the motor used in the preferred embodiment of the present invention, the normal field coil energizing voltage is IIIJ. volts. If field coils 4|- and 42 are connected in parallel with field coils 43 and 44, the motor will function properly with the normal energizing voltage impressed thereon. This parallel connection may be obtained by turning knob I5 to its extreme counterclockwise position thereby establishing a circuit from line wire through contactor member 35, wire 45, field coils 4|, 42-, wire 46, contactor member 36, contactor 36, contact pin 22, contactor 46, contactor member, to line wire 55. Field coils 43 and 44 are connected to line wires 55. and 56:from contactor member 35, through contactor 35', contact pin 2I, contactor 36, contactor member 39, wire 41, coils 43 and 44, wire 48, to contactor 40' and line 56.

By turning knob I5 to its extreme clockwise position, the field coils are all connected in series, thus necessitating the use of 220 volts line voltage. Fig. 5 is an illustration of the position ofthe switch when 220 volt operation is desired, the motor being provided with power as follows: Line wire 55 to contactor 35, wire 45, field coils M, 42, wire 45, contactor member 36, contactor- Y termines the direction of rotation of the motor,

turning the knob I4 to its opposite positions will;

eifectively change this polarity and the direc-...

tion of rotation of the motor. Power is fed;- through line wire 55 to contactor 35, wire 45; field.- coilsv M and' 4.2, Wire 46, contactor member 36,

contactor 36', contact pin 2I, contactor 39', (Fig 4) contact pin-v I9, contact pin 25, bridge 28-, closed contacts 3| and 32, contact arm 33, wire 541,; starting Winding- 52, 5|, 5|], 49, wire 53-, contact pin 23, bridge 21, contactpins 24 and 20, con-.

tactor 40' and thence to line 56-. By turning the knob I 4' to its maximum counterclockwise post-N tion, contact pins I9 and 20 will be brought out of registry with pins 25 and 24-, respectively, and brought into registry with pins- 23 and 26, respectively, thereby establishing a circuit from line 55 through contactor 35, wire 45, coils 4I-', 42-, wire 46, contactor member 36, contactor 36, contact pin 2I, contactor 39, contactpin I9, contactpin 23, wi e .3-, s ar in c ls; .0. 5t. 5 r

54, contact arm 33, closed contacts 32, 3|, bridge 28 contact pins 26 and 20, contactor 40', contactor member 40, and thence to line 56.

The same effective circuit is established even though disc i3 is rotated to its extreme counterclockwise position, a circuit being established from line 55 through contactor member 35, contactor 35', contact pin El, contactor 39, contact pin l8, contact pin 23, wire 53, starting coils 49, 59, 5t, 52, wire 54, contact arm 33, closed contacts 32, Si, bridge 23, contact pins 26 and 20, contactor id, contactor member 48, and thence to line 58.

Any means well known to the art may be used to actuate the contactor arm 33 to produce the necessary starting torque in the single phase motor utilized in the preferred embodiment of the present invention.

I claim as my invention:

1. A switch of the character described including a series of coaxially disposed contiguous discs of insulating material, a like number of concentrically arranged shafts axially secured to said discs for independent rotation of any of said discs, two contact pins associated with each of said discs, two oppositely disposed spring contactor members arranged over the upper of said discs to register with both of said contact pins mounted in said upper disc when said disc is rotated to one position, and only one of said members to register with one of said last-named contact pins, when said disc is rotated to its other position, a second pair of oppositely disposed spring contactor members sandwiched between adjacent discs each being in continuous engagement with one of said contacts in said upper disc, said last-named members being oppositely registrable with each of said contact pins in the lower of said discs, and a third pair of oppositely disposed contactor members positioned immediately below said lower disc to oppositely register with each of said last-named contactor members.

2. A switch of the character described including two coaxially disposed contiguous discs of insulating material, a like number of concentrically arranged shafts, each being axially secured to one of said discs for independent rotation of either of said discs, two diametrically spaced contact pins for each of said discs, each penetrating its disc near the periphery thereof, a first pair of oppositely disposed contactor members alternatively registrable with each and then only one of said contact pins in the upper of said discs, a second pair of oppositely disposed contactor members sandwiched between said discs being in continuous engagement with said contact pins in said upper disc, said last-named members alternatively registrable with each of said contact pins in the lower of said discs, and a third pair of oppositely disposed contactor members alternatively registrable with each of said contact pins in said lower disc.

3. A switch of the character described including two coaxially disposed contiguous discs of insulating material, a like number of concentrically arranged shafts, each being axially secured to one of said discs for independent rotation of either of said discs, a knob fixedly asso ciated with each of said shafts at a point remote from its disc, a spiral compression spring concentrically associated with said shafts, means associated with said shafts and limiting movement of said discs under the influence of said spring, two diametrically spaced contact pins for each of said discs, each penetrating its disc near the periphery thereof, a first pair of oppositely arranged contactor members, contactors being formed integral therewith disposed over said upper disc, one of said contactors being formed to substantially resemble a quarter section of an annulus, the other of said contactors being formed to substantially resemble an eighth section of the same annulus, both of said contactors being severally registrable with said contact pins for one position of said upper disc while only the first-named contactor of said contactors is registrable with one of said contact pins for the other position of said upper disc, a second pair of oppositely disposed contactor members, contactors formed integral therewith, said second pair of members being spaced degrees from said first pair of members, said last named contactors formed substantially like the first-named contactor being sandwiched between said discs, said last-named contactors being in continuous engagement with said contact pins in said upper disc and alternatively in engagement with said contact pins in the lower of said discs, a third pair of oppositely disposed contactors disposed under said lower disc and aligned with said firstnamed members, and said third pair of contactors formed substantially like the first-named contactor being alternatively registrable with each of said contact pins in said lower disc.

LAWRENCE E. THOMPSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 390,904 Ries Oct. 9, 1888 1,663,779 Soreng Mar. 2'7, 1928 1,906,463 Hamm May 2, 1933 

